CN105980098A - Beam shaping mask, laser processing device, and laser processing method - Google Patents

Abstract

The present invention relates to a beam shaping mask, a laser processing apparatus, and a laser processing method. It is a beam shaping mask (1) having an opening (4) with a shape similar to the shape of an opening pattern (20) to be laser-processed on a thin film (15). The opening (4) is formed such that the light transmittance within the opening (4) decreases from the center to the periphery, and even at the periphery, it has a light transmittance sufficient to ensure at least a minimum laser intensity to laser-process the thin film (15), thereby preventing burrs (22) from forming at the edges of the laser-processed hole.

Description

Beam shaping mask, laser processing device and laser processing method

technical field

The present invention relates to a beam shaping mask having an opening similar to the shape of a hole machined by laser on an object to be processed, and more particularly to a beam shaping mask intended to prevent burrs from being generated at the edge of the laser machined hole. Die, laser processing device and laser processing method.

Background technique

In the past, such a beam shaping mask is a mask used in a projection imaging laser ablation system, which has a pattern similar to the aperture formed on a flexible film. By imaging the pattern on the above-mentioned film, the film After laser ablation, pores with the above-mentioned pore size are formed in the thin film (for example, refer to Patent Document 1).

Patent Document 1: Japanese Patent Laid-Open Publication No. 2005-517810

However, in such a conventional beam shaping mask, the above-mentioned pattern is an opening having a shape similar to the aperture formed on the film, and since the light transmittance in the opening is constant throughout the entirety, the light transmittance in the opening may be changed when using the transmittance. Cutting residue (hereinafter referred to as "burr") occurs at the edge of the aperture processed by the patterned (opening) laser passing through the film due to uneven in-plane intensity distribution of the laser. Therefore, fine through-holes having the above-mentioned pore diameters cannot be precisely formed in the thin film.

Contents of the invention

Therefore, in order to solve such problems, an object of the present invention is to provide a beam shaping mask, a laser processing device, and a laser processing method for preventing burrs from being generated at the edge of a laser processed hole.

In order to achieve the above objects, the beam shaping mask of the present invention is a beam shaping mask having an opening similar in shape to a hole formed by laser processing on a workpiece, and the opening is formed so that the light transmittance in the opening is It decreases gradually from the central portion to the peripheral portion, and has a light transmittance capable of securing at least the minimum laser intensity capable of laser processing the above-mentioned workpiece even at the peripheral portion.

In addition, the laser processing device of the present invention is a laser processing device for reducing and projecting the opening formed on the beam shaping mask on the workpiece, and laser processing holes on the workpiece. For the above beam shaping mask, The opening is formed such that the light transmittance in the opening decreases gradually from the central portion to the peripheral portion, and even the peripheral portion has a light transmittance capable of ensuring at least a minimum laser intensity capable of laser processing the workpiece.

In addition, the laser processing method of the present invention is a laser processing method in which the aperture formed on the beam shaping mask is reduced and projected on the workpiece, and the laser processing hole is laser processed on the workpiece, and the laser beam emitted multiple times is transmitted to The light transmittance in the opening decreases gradually from the central portion to the peripheral portion, and the light transmittance in the peripheral portion can ensure at least the minimum laser intensity capable of laser processing the workpiece. The above-mentioned opening in the mold is used to irradiate the above-mentioned workpiece with the above-mentioned multiple-shot laser beam transmitted through the above-mentioned opening to process the above-mentioned hole in the above-mentioned workpiece.

According to the present invention, it is possible to prevent burrs from being generated at the edge of the laser-processed hole. Therefore, fine holes can be precisely formed in the workpiece.

Description of drawings

FIG. 1 is a view showing an embodiment of a beam shaping mask of the present invention, FIG. 1( a ) is a plan view, and FIG. 1( b ) is a cross-sectional view along line O-O of FIG. 1( a ).

2 is a diagram illustrating the light transmittance in the opening of the beam shaping mask of the present invention, and FIG. 2(a) is a graph showing an example of the light transmittance characteristics along the center line in the opening. (b) is an explanatory diagram showing a halftone, and FIG. 2(c) is an explanatory diagram showing an example of halftone formation in FIG. 2(b).

FIG. 3 is an explanatory diagram showing a schematic configuration of an embodiment of the laser processing apparatus of the present invention.

4 is a view showing a conventional beam shaping mask, FIG. 4( a ) is a plan view, and FIG. 4( b ) is a graph showing an example of the light transmittance characteristics along the center line in the opening.

5 is an explanatory diagram showing an example of laser processing using a beam shaping mask of the prior art, wherein (a) of FIG. 5 shows the start of laser irradiation, (b) of FIG. ) indicates the state after laser processing.

FIG. 6 is an explanatory diagram showing a cross-sectional example of laser processing using the beam shaping mask of the present invention.

FIG. 7 is an explanatory diagram showing a planar example of laser processing using the beam shaping mask of the present invention.

detailed description

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. FIG. 1 is a view showing an embodiment of a beam shaping mask of the present invention, FIG. 1( a ) is a plan view, and FIG. 1( b ) is a cross-sectional view along line O-O of FIG. 1( a ). In addition, FIG. 2 is a diagram illustrating the light transmittance in the opening of the beam shaping mask of the present invention, and (a) of FIG. 2 is a graph showing an example of the light transmittance characteristics along the center line in the opening. 2(b) is an explanatory diagram showing a halftone, and FIG. 2(c) is an explanatory diagram showing an example of halftone formation in FIG. 2(b). This beam shaping mask 1 has an opening similar to the shape of a hole to be processed by laser processing, and is configured to include a transparent substrate 2 , a light-shielding film 3 , and an opening 4 .

The above-mentioned transparent substrate 2 is, in particular, a quartz substrate, for example, which transmits laser light having a wavelength of 400 nm or less capable of ablating a resin thin film which is a sheet-shaped workpiece with high transmittance. Alternatively, a transparent glass substrate may also be used.

The light-shielding film 3 is provided so as to cover one surface of the above-mentioned transparent substrate 2 . The light-shielding film 3 blocks the transmission of laser light and is, for example, a metal film made of chromium (Cr) with a thickness of about 100 nm, and is formed on the transparent substrate 2 by known film-forming techniques such as sputtering and vapor deposition.

An opening 4 is provided in the above-mentioned light shielding film 3 . The opening 4 is used to shape the cross-sectional shape intersecting with the optical axis of the laser beam irradiated on the film, and is formed on the light-shielding film 3 to allow the laser light to pass through, and has the same opening pattern as the laser processed on the film. A plurality of similar shapes to the shape of the holes are arranged vertically and horizontally as shown in FIG. 1( a ).

Specifically, as shown in (a) of FIG. 2 , the opening 4 is formed such that the light transmittance in the opening 4 gradually decreases from the central part to the peripheral part, and even at the peripheral part, it is possible to ensure laser processing (ablation). The light transmittance of at least the minimum laser intensity of the above-mentioned thin film is, for example, about 60%. The decreasing manner of the above-mentioned light transmittance may be linear or non-linear.

In order to have the characteristic that the light transmittance in the opening 4 gradually decreases from the central portion to the peripheral portion as described above, the opening 4 shown in FIG. 2( b ) may be half-tone. Therefore, as shown in (c) of the figure, it is also possible to form a plurality of metal films in the same manner as the above-mentioned light-shielding film 3 in the opening 4 in such a manner that the size becomes larger or the arrangement density becomes higher from the central part to the peripheral part. shading point 5. In addition, the size of the shading point 5 may be smaller than the resolution of the optical system composed of the imaging lens 9 and the objective lens 10 . Alternatively, in order to gradually decrease the light transmittance in the opening 4 from the central portion to the peripheral portion, a plurality of shielding lines may be formed such that their width becomes larger or the arrangement density thereof increases from the central portion to the peripheral portion. In order to form the above-mentioned opening 4 on the light-shielding film 3, a photoresist is applied so as to cover the light-shielding film 3, and a photomask is used to expose and image the above-mentioned photoresist to form a resist mask. After molding, the portion of the light-shielding film 3 exposed on the surface is removed by known etching techniques such as wet etching and dry etching, thereby forming the opening 4 .

In the case of forming the opening pattern of the thin film by laser irradiation of multiple shots, it is necessary to make the laser intensity projected on the peripheral portion of the above-mentioned opening 4 of the thin film the lowest value at which the thin film can be ablated even in the laser processing of one shot. . Thus, the above-mentioned projected portion of the film corresponding to the opening 4 is completely ablated and removed by multiple irradiations of the laser, thereby forming the above-mentioned opening pattern on the film. In this case, since the holes of the opening pattern gradually expand from the center to the periphery of the film, there is no possibility of burrs being generated on the periphery of the opening pattern.

Next, an embodiment of a laser processing apparatus including the beam shaping mask 1 of the present invention will be described. FIG. 3 is an explanatory diagram showing a schematic configuration of an embodiment of the laser processing apparatus of the present invention.

The laser processing apparatus described above includes an XY stage 6, a laser light source 7 located above the XY stage 6 from upstream to downstream in the traveling direction of the laser light L, a coupling optical unit 8, a beam shaping mask 1, and an imaging lens in this order. 9 and objective lens 10. In addition, on the optical path from the objective lens 10 toward the imaging lens 9, a photographing camera 12 is arranged on the optical path branched by the half mirror 11, and on the optical path from the objective lens 10 toward the imaging lens 9, the laser light L of a wavelength below 400 nm is transmitted and passed by An illumination light source 14 is disposed on the optical path branched by the dichroic mirror 13 that reflects visible light.

Here, the XY stage 6 is a stage on which a resin film 15 through which visible light is transmitted is placed on the upper surface, and moves in the X and Y directions in a plane parallel to the XY plane, and is controlled by a control device (not shown). , stepping to move the amount of movement input and stored in advance.

The above-mentioned laser light source 7 is a YAG laser that emits, for example, KrF248nm excimer laser light that generates laser light L with a wavelength of 400nm or less, or 1064nm third harmonic or fourth harmonic laser light L. Laser light L may be infrared rays or visible rays, but ultraviolet rays are preferable for ablating the thin film 15 .

The coupling optical unit 8 includes a beam expander that expands the laser beam emitted from the laser light source 7, an optical integrator that uniformly irradiates the luminance distribution of the laser light L to the beam shaping mask 1 described later, and a condenser lens.

The above-mentioned beam shaping mask 1 shapes the laser light L irradiated to the film 15 into a plurality of laser beams L having a cross-sectional shape similar to the shape of the opening pattern processed by the laser and emits them, as shown in FIG. For the opening pattern formed in the thin film 15, the plurality of aperture patterns formed at a preset predetermined magnification M is arranged at a pitch M times the arrangement pitch of the plurality of opening patterns located in a preset unit area. Each opening 4 is formed on a light-shielding film 3 of chromium (Cr) or the like covered on a transparent quartz substrate.

Specifically, the above-mentioned beam shaping mask 1 has an opening 4 having a shape similar to the opening pattern as described above, and is configured so that the light transmittance in the opening 4 increases from the center to the periphery as shown in FIG. Even at the peripheral portion, it is possible to secure a light transmittance of, for example, about 60% of at least the minimum laser intensity capable of laser processing the thin film 15 .

The imaging lens 9 cooperates with the objective lens 10 described below to reduce and project the openings 4 formed in the beam shaping mask 1 onto the film 15 at a preset magnification M, and the imaging lens 9 is a condenser lens.

Furthermore, the above-mentioned objective lens 10 cooperates with the above-mentioned imaging lens 9 to reduce and project the plurality of openings 4 formed in the beam shaping mask 1 on the film 15 at a preset magnification M, and is arranged, for example, on the side of the film 15. On the back side, an image of the above-mentioned reference pattern on the transparent reference substrate 16 provided with the reference pattern as the reference pattern for positioning of the irradiation of the laser light L is acquired, and can be photographed by the imaging camera 12 described below. Then, the imaging position of the objective lens 10 and the beam shaping mask 1 are in a conjugate relationship.

The photographing camera 12 photographs the reference pattern provided on the reference substrate 16 and is, for example, a CCD camera or a CMOS camera that captures a two-dimensional image. Then, the imaging position of the objective lens 10 and the imaging plane of the imaging camera 12 are in a conjugate relationship.

The illumination light source 14 is, for example, a halogen lamp that emits visible light, and illuminates an imaging area of the imaging camera 12 to enable imaging by the imaging camera 12 .

In addition, in FIG. 3 , reference numeral 17 is an image formed by cooperating with the objective lens 10 to image the image of the reference pattern on the reference substrate 16 , the image of the opening pattern 20 formed by laser processing, etc. on the imaging surface of the imaging camera 12 . Lenses, reference numeral 18 is a relay lens, and reference numeral 19 is a total reflection mirror.

Next, the laser processing method performed using the laser processing apparatus comprised in this way is demonstrated. Here, a case where an opening pattern is formed on the thin film 15 will be described.

First, the reference substrate 16 is placed and fixed on the XY stage 6 so that the surface 16 a on which the reference pattern is formed is the side of the XY stage 6 , and the reference substrate 16 is placed on the surface opposite to the surface 16 a on which the reference pattern is formed. 16b is closely attached to the film 15.

Next, the XY stage 6 is moved, and the objective lens 10 is set at the laser processing start position of the thin film 15 . Specifically, the reference pattern provided on the above-mentioned reference substrate 16 corresponding to the center position of the unit area of the laser processing start position is photographed by the imaging camera 12 through the film 15, and the reference pattern is positioned at the imaging center. . In addition, the imaging center coincides with the optical axis of the objective lens 10 .

Next, the laser optical unit of the laser processing device is raised along the optical axis of the objective lens 10 in the Z-axis direction by a predetermined distance, and the imaging position of the objective lens 10 is positioned on the interface between the film 15 and the above-mentioned reference substrate 16 .

Next, the laser light source 7 is activated to perform pulse oscillation to emit the laser light L irradiated multiple times. The emitted laser light L is expanded by the coupling optical unit 8 and irradiated to the beam shaping mask 1 so as to become the laser light L with a uniform intensity distribution.

The laser light L irradiated to the beam shaping mask 1 passes through the plurality of openings 4 of the beam shaping mask 1, and the cross-sectional shape intersecting the optical axis is shaped into a shape similar to the shape of the opening pattern to become a plurality of openings 4. The laser light L is emitted from the beam shaping mask by means of light. Then, the light is focused on the film 15 by the objective lens 10 .

In this case, in the conventional beam shaping mask 1 shown in FIG. The in-plane intensity distribution of the shaped laser light L has unevenness within an allowable range and is substantially uniform as a whole. Therefore, when the thin film 15 is processed by such laser light L, from the start time of laser irradiation shown in (a) of FIG. The hole 21 of the opening pattern 20 is formed at a depth of . However, before the hole 21 of the opening pattern 20 penetrates the thin film 15 , there are portions where the hole 21 of the opening pattern 20 penetrates and a portion where the hole 21 does not penetrate due to uneven in-plane intensity distribution of the laser light L. Therefore, as shown in (c) of the figure, burrs 22 are generated on the edge portion of the opening pattern 20 on the side opposite to the laser irradiation side.

On the other hand, in the present invention, as shown in (a) of FIG. 2 , since the light transmittance in the above-mentioned opening 4 gradually decreases from the central portion to the peripheral portion, the ablation film 15 can be ensured even at the peripheral portion. The mode of laser intensity obtains the minimum also is the light transmittance of about 60%, therefore, as shown in (a) of Fig. 6 and Fig. 7 (a), on film 15, process hole 21 from the strong central part of laser intensity , through the irradiation of the laser light L irradiated multiple times, the hole 21 gradually increases in depth and becomes larger as shown in (b) to (d) of FIG. 6 and (b) to (d) of FIG. 7 , Thus, as shown in FIG. 6( e ) and FIG. 7( e ), finally the opening pattern 20 is formed through the thin film 15 .

Thus, according to the present invention, since the hole 21 of the opening pattern 20 is gradually enlarged from the center to the periphery of the film 15 , there is no possibility of burr 22 being generated on the periphery of the opening pattern 20 .

Thus, if a plurality of opening patterns 20 are formed in the unit area of the laser processing start position, the XY stage 6 is moved stepwise in the X or Y axis direction by a predetermined distance, and the second unit area, A plurality of opening patterns 20 are sequentially laser processed in each unit area such as the third unit area . . . In this way, a plurality of opening patterns 20 can be formed at predetermined positions set in advance on the film 15 .

To form a plurality of opening patterns 20, as described above, the reference pattern provided on the above-mentioned reference substrate 16 corresponding to, for example, the center position of the unit area of the laser processing start position is photographed by the imaging camera 21, and the above-mentioned reference pattern is confirmed. After the position of the reference pattern is set, the XY stage is moved in steps in the X and Y directions using the position of the reference pattern as a reference. At this time, based on the mechanical accuracy of the XY stage 6, a plurality of opening patterns 20 may be formed in each unit area while stepping and moving a predetermined distance set in advance, or the center and center of each unit area may be photographed by the imaging camera 12. The positions are correspondingly provided on the reference pattern of the reference substrate 16 , and after positioning, for example, the imaging center of the imaging camera 12 (coinciding with the optical axis of the objective lens 10 ) on the reference pattern, the plurality of opening patterns 20 are laser processed. In addition, a plurality of opening patterns 20 may be formed by irradiating the thin film 15 with a single laser L passing through one opening 4 provided in the beam shaping mask 1 while moving the XY stage by a predetermined predetermined distance in steps.

In addition, in the above-mentioned embodiment, although the case of moving the XY stage 6 in the two-dimensional direction of XY has been described, the present invention is not limited thereto, and the laser optical unit side including the objective lens 10 may be moved or Both the stage and the laser optical unit are relatively moved.

In addition, in the above-mentioned embodiment, although the case where the object to be processed is the resin film 15 has been described, the present invention is not limited thereto, and the object to be processed may be a laminated film 15 including at least one opening pattern 20 described above. The above-mentioned film 15 is a laminate of a metal mask and a resin film 15 of a through hole of a size. Alternatively, the workpiece may be a sheet-shaped metal foil.

Explanation of reference signs

1...beam shaping mask; 4...aperture; 15...thin film (processed object); 20...opening pattern (hole of processed object); L...laser.

Claims (10)

1. a beam shaping mask, it has and the shape in the hole being lasered in machined object The opening of the shape that shape is similar, described beam shaping mask is characterised by,

The light transmission that described opening is formed in this opening successively decrease to circumference from central part and Even and if circumference also have be able to ensure that can laser machine described machined object The light transmission of the laser intensity of low limit.

Beam shaping mask the most according to claim 1, it is characterised in that

Described opening is provided with multiple in vertical and horizontal arrangement.

Beam shaping mask the most according to claim 1 and 2, it is characterised in that

The hole of described machined object is formed by the repeatedly irradiation of laser.

Beam shaping mask the most according to claim 1 and 2, it is characterised in that

Described machined object is resinous thin film.

Beam shaping mask the most according to claim 3, it is characterised in that

Described machined object is resinous thin film.

6. a laser processing device, the opening being formed on beam shaping mask is reduced throwing by it Shadow, on machined object, laser machines hole, the spy of described laser processing device on this machined object Levy and be,

For described beam shaping mask, described opening is formed as the light transmission in this opening Even if rate is successively decreased to circumference from central part and also has at circumference that be able to ensure that can laser Process the light transmission of the most MIN laser intensity of described machined object.

Laser processing device the most according to claim 6, it is characterised in that

The hole of described machined object is formed by the repeatedly irradiation of laser.

8. according to the laser processing device described in claim 6 or 7, it is characterised in that

Described machined object is resinous thin film.

9. a laser processing, the opening being formed on beam shaping mask is reduced throwing by it Shadow, on machined object, laser machines hole, the spy of described laser processing on this machined object Levy and be,

Make the laser transmission repeatedly irradiated with the light transmission in described opening from central part to periphery Even if successively decreasing in portion and also has at circumference and be able to ensure that and can laser machine described machined object The mode of light transmission of the most MIN laser intensity be formed on described beam shaping Described opening on mask,

The described laser repeatedly irradiated that will transmit through described opening expose to described machined object and Described machined object is processed described hole.

Laser processing the most according to claim 9, it is characterised in that

Described machined object is resinous thin film.